1. Field of the Invention
This invention relates a heat-sensitive recording material with excellent printability and image storability.
2. Related Art
Recently, heat-sensitive recording materials capable of recording by use of thermal energy have come to be used in a variety of recording and printing devices such as printers or recorders for various types of measuring apparatus, labelling printers, POS printers and automatic vending machines for tickets or such.
The conventional heat-sensitive recording materials using an electron donative colorless dye precursor and an electron accepting color developer, while having various advantageous properties such as good appearance, good touch, high developed color density and various kinds of developed color hue, also had the defect that the image storability was poor; the recorded image portion (heat-sensitive color-forming portion) could disappear by the action of a plasticizer or additive(s) contained in a plastic such as polyvinyl chloride when contacted with the plastic, or were apt to disappear upon contact with chemicals contained in foods or cosmetics or to discolor on exposure to sunlight for a short period of time.
Various attempts have been made for overcoming said prior art problem of poor image storability. For example, U.S. Pat. Nos. 4,521,793, 4,824,824 and 4,880,767 disclose two-component thermal recording materials which are capable of forming a recorded image with good storability as a result of thermal reaction of the two components: an isocyanate compound and an imino compound.
However, these thermal recording materials comprising an imino compound and an isocyanate compound, although excellent in recorded image storability, has the defect that the heat-sensitive recording layer is partially picked off when functional side of the materials is printed (hereinafter referred to as "picking off"). Therefore, said thermal recording materials were unsuited for application to the printing or recording systems where printing has to be conducted on the recording layer, such as CD/ATM or handly terminals where the printouts of thermal recording material are used as a receipt or a notice. Thus, the improvement on this type of recording material has been keenly desired in the art.
In view of the above, the present invention is aimed at developing an image recording material having excellent printability and image storability.